Ok, what's the point you're trying to make? In the early beginning I have had DeLonghi and it most certainly didn't have any OPV.

Well you made some statements in your previous comment about pressure which suggested they were generally applied to espresso making. That simply isn't true.

Espresso machines without OPV are really a minority. Even single-boiler entry level machines like the Gaggia Classic or the Rancilio Silva have an OPV.

Parent comment seemed to suggest that (much) higher pressure produces better espresso and my comment had a sole intent, at the expense of simplifying some things, to give some grounds why espresso manufacturers might use higher than 9-10 bar pressure at the pump.

Gaggia Classic is a 350 EUR machine whereas Rancilio Silvia is 600 EUR machine. These are not entry level machines. They are entry level for someone becoming more interested in espresso but not for ordinary people. And ordinary people do not spend 400-500 EUR for a coffee machine if they think they are going to get the same for twice less money. Twice less money machines do not have OPV.

> These are not entry level machines

Yes they are. To put some perspective, my current machine (Bezzera BZ10) costs about $1,700 USD and it's not even close to being a high end machine.

Respectfully, you don't know what you're talking about. Even the Delongi Dedica, which is at the bottom end of espresso machines, has an OPV valve.

Without a pressure release, they might explode right? Seems bad, I would expect it to be standard equipment.

They are not going to explode but on such machines if you remove the portafilter straight after extracting the espresso, the puck will "explode" and is going to create a mess. In more expensive machines this is regulated through OPV and solenoid valve through which the pressure built up is going to be released.